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Granular Sludge (granular + sludge)
Kinds of Granular Sludge Selected AbstractsBonding Form Analysis of Metals and Sulfur Fractionation in Methanol-Grown Anaerobic Granular SludgeENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2007A. van der Veen Abstract This study investigates the metal and sulfur bonding form distribution in mesophilic (30,°C, pH 7) methanol-grown anaerobic granular sludge from upflow anaerobic sludge bed reactors operating at an organic loading rate of 3.8,g CH3OH-COD/L d. This was achieved by applying a modified Tessier sequential extraction scheme to investigate the metal bonding forms and a sequential extraction scheme for sulfur and simultaneously extracted metals to granular sludge samples of the reactors after 0, 22, 35 and 43 days of operation. Metals were also determined in the sulfur extracts. Co and Ni predominated in their oxidizable bonding forms, which increased together with the pseudo-total content during reactor operation. An omission of Co and Ni from the influent led to only a minor decline of the pseudo-total content in the sludge, mainly from the acid-soluble fraction. The ratio of simultaneously extracted metals (Co, Fe, Mn, Ni) to acid-volatile sulfides was lower than 1, indicating that the sludge contained sufficient sulfide to bind the metals as metal monosulfides. The bioavailability of metals in the methanol-grown anaerobic granular sludge investigated is therefore mainly controlled by sulfide formation/dissolution. [source] Trace Metals in Anaerobic Granular Sludge Reactors: Bioavailability and Dosing StrategiesENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 3 2006H. Zandvoort Abstract The trace metal dynamics in anaerobic granular sludge bed reactors and their influence on reactor performance is reviewed in this paper. An insight into the metal dynamics is required from a practical point of view in order to be able to early recognize limitations for essential trace elements, viz., to know when dosing of these elements is required in full-scale anaerobic bioreactor applications. Further such knowledge is indispensable for a rational dosage of these metals, e.g., to ensure maximum substrate conversion rates and to prevent disturbances in reactor performance using a minimum amount of metals. Therefore, the retention, accumulation and release of trace metals in anaerobic granular sludge and the factors affecting these processes need to be known. [source] Changes in microbial community composition following treatment of methanogenic granules with chloroformENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2009Bo Hu Abstract Eliminating hydrogen consuming bacteria is a critical step in anaerobic fermentation for biohydrogen production. Treatment of anaerobic granular sludge with chloroform was reported as effective in transforming a methane-producing system into a hydrogen-producing system by eliminating methane production. This study, using 16S rRNA gene sequences, further assessed changes in microbial community composition as a result of chloroform treatment and during continuous cultivation of chloroform-treated granules in a continuous upflow reactor employing immobilized cells. Profiles of terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes sequences cloned from samples before and after chloroform treatment showed that methanogenic hydrogen consumers and Methanosaeta harundinacea sp. were eliminated. Methanosaeta concilii, however, was not eliminated from the hydrogen-producing system, which might explain, in part, the granulation phenomena in the anaerobic hydrogen fermentation system. The results also showed that Clostridium butyricum dominated the hydrogen-production system. © 2009 American Institute of Chemical Engineers Environ Prog, 2009 [source] Molecular monitoring of microbial diversity in expanded granular sludge bed (EGSB) reactors treating oleic acidFEMS MICROBIOLOGY ECOLOGY, Issue 2 2002Maria Alcina Pereira Abstract A molecular approach was used to evaluate the microbial diversity of bacteria and archaea in two expanded granular sludge bed (EGSB) reactors fed with increasing oleic acid loading rates up to 8 kg of chemical oxygen demand (COD) m,3 day,1 as the sole carbon source. One of the reactors was inoculated with granular sludge (RI) and the other with suspended sludge (RII). During operation, the sludge in both reactors was segregated in two layers: a bottom settled one and a top floating one. The composition of the bacterial community, based on 16S rDNA sequence diversity, was affected most during the oleate loading process in the two reactors. The archaeal consortium remained rather stable over operation in RI, whereas in RII the relative abundance of Methanosaeta -like organisms became gradually weaker, starting in the bottom layer. In the range of oleate loads evaluated, 6 kg of COD m,3 day,1 was found as the maximum value that could be applied to the system. A further increase to 8 kg of oleate-COD m,3 day,1 induced a maximal shift on the microbial structure of the sludges. At this time point, methanogenic acetoclastic activity was not detected and only very low methanogenic activity on H2/CO2 was exhibited by the sludges. [source] Assessment of anaerobic wastewater treatment failure using terminal restriction fragment length polymorphism analysisJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2005C. Scully Abstract Aims:, The suitability of genetic fingerprinting to study the microbiological basis of anaerobic bioreactor failure is investigated. Methods and Results:, Two laboratory-scale anaerobic expanded granular sludge bed bioreactors, R1 and R2, were used for the mesophilic (37°C) treatment of high-strength [10 g chemical oxygen demand (COD) l,1] synthetic industrial-like wastewater over a 100-day trial period. A successful start up was achieved by both bioreactors with COD removal over 90%. Both reactors were operated under identical parameters; however, increased organic loading during the trial induced a reduction in the COD removal of R1, while R2 maintained satisfactory performance (COD removal >90%) throughout the experiment. Specific methanogenic activity measurements of biomass from both reactors indicated that the main route of methane production was hydrogenotrophic methanogenesis. Terminal restriction fragment length polymorphism (TRFLP) analysis was applied to the characterization of microbial community dynamics within the system during the trial. The principal differences between the two consortia analysed included an increased abundance of Thiovulum - and Methanococcus -like organisms and uncultured Crenarchaeota in R1. Conclusions:, The results indicated that there was a microbiological basis for the deviation, in terms of operational performance, of R1 and R2. Significance and Impact of the Study:, High-throughput fingerprinting techniques, such as TRFLP, have been demonstrated as practically relevant for biomonitoring of anaerobic reactor communities. [source] Microscopic observation of aerobic granulation in sequential aerobic sludge blanket reactorJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2001J.-H. Tay Aims: This paper attempts to provide visual evidence of how aerobic granulation evolves in sequential aerobic sludge blanket reactors. Methods and Results: A series of experiments were conducted in two column-type sequential aerobic sludge reactors fed with glucose and acetate as sole carbon source, respectively. The evolution of aerobic granulation was monitored using image analysis and optical and scanning electron microscopy. The results indicated that the formation of aerobic granules was a gradual process from seed sludge to compact aggregates, further to granular sludge and finally to mature granules with the sequential operation proceeding. Glucose- and acetate-fed granules have comparable characteristics in terms of settling velocity, size, shape, biomass density and microbial activity. However, the microbial diversity of the granules was associated with the carbon source supplied. In this work, an important aerobic starvation phase was identified during sequential operation cycles. It was found that periodical aerobic starvation was an effective trigger for microbial aggregation in the reactor and further strengthened cell,cell interaction to form dense aggregates, which was an essential step of granulation. The periodical starvation-induced aggregates would finally be shaped to granules by hydrodynamic shear and flow. Conclusions: Aerobic granules can be formed within 3 weeks in the systems. The periodical starvation and hydrodynamic conditions would play a crucial role in the granulation process. Significance and Impact of the Study: Aerobic granules have excellent physical characteristics as compared with conventional activated sludge flocs. This research could be helpful for the development of an aerobic granule-based novel type of reactor for handling high strength organic wastewater. [source] Anaerobic digestion of Aegean olive mill effluents with and without pretreatmentJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2010Gülseren Pekin Abstract BACKGROUND: Olive oil production is an important economical activity in the Aegean region of Turkey. However, the effluents of the olive oil producing mills with their high organic loads and toxic compounds are causing serious environmental problems. The anaerobic biological treatment of olive mill wastewater (OMWW) using the treatment plants of the regional industries could be a method of choice and within the scope of this study floccular and granular sludges were investigated in batch mode for their success in the treatment of OMWW while producing biogas. The major limitation of this treatment is the inhibition of methanogenic bacteria by the phenolic compounds in OMWW. Thus an integrated solution was suggested in which a pre-treatment step (dephenolization) was also introduced before biological step. RESULTS: The effluents of 27 olive mills out of 47 were found to have total phenolics (TP) less than 3 g L,1 and could be treated anaerobically after simple dilution. The biogas production for the untreated OMWW was higher for floccular sludge than for the granular sludge (68.5 mL and 45.7 mL respectively). Combined pre-treatment experiments, first coagulation with polyaluminum chloride, followed by flocculation with cationic polyelectrolyte and finally Fenton's oxidation, could remove 80% of TP and 95% of the total suspended solids. CONCLUSION: OMWW having TP values less than 3 g L,1 can be treated anaerobically using floccular sludge after simple dilution and biogas can be produced. For OMWW samples having higher TP values pre-treatment is necessary and the pre-treatment given in this study may be used effectively. Copyright © 2010 Society of Chemical Industry [source] Aerobic granules for low-strength wastewater treatment: formation, structure, and microbial communityJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2009Shu-Guang Wang Abstract BACKGROUND: To validate the possibility of aerobic granulation at a lower organic loading rate (OLR) than 2 kg COD m,3 day,1 (GS 1) in a sequencing batch reactor (SBR), the formation, structure, and microbial community of granular sludge (GS) were investigated. RESULTS: The overall experimental process involved the following stages: acclimation, granulation, maturation, and stabilization. The optical microscopic showed the structural changes from fluffy activated sludge (AS) to GS and scanning electron microscope (SEM) examination revealed that GS 1 was irregular filamentous aggregates composed mainly of various filamentous species, while the aerobic granules cultivated at OLR 1.68,4.20 kg COD m,3 day,1 (GS 2) was mycelial pellets consisting of fungi and filamentous microorganisms. A Biolog Ecoplate analysis indicated that significant differences existed between the microbial community structure and the substrate's utilization of AS and different GS samples. CONCLUSION: GS 1 was achieved and different from GS 2 in the formation, structure, and microbial community. Aerobic granulation with low strength wastewater is of importance for the full-scale application of this technology. Copyright © 2009 Society of Chemical Industry [source] Anaerobic biodegradation of phenol in sulfide-rich mediaJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2004Patricia Olguín-Lora Abstract In the refinery industry, the washing processes of middle-distillates using caustic solutions generate phenol- and sulfide-containing waste streams. The spent caustic liquors generated contain phenols at concentrations higher than 60 g dm,3(638.3 mmol dm,3). For sulfur compounds, the average sulfide concentration was 48 g dm,3(1500 mmol dm,3) in these streams. The goal of this study was to evaluate the specific impact of phenol and sulfide concentrations towards the phenol-biodegradation activity of a phenol-acclimated anaerobic granular sludge. An inhibition model was used to calculate the phenol and sulfide inhibitory concentrations that completely stopped the phenol-biodegradation activity (IC100). A maximum phenol-biodegradation activity of 83 µmol g,1 VSS h,1 was assessed and the IC100 values were 21.8 mmol dm,3 and 13.4 mmol dm,3 for phenol and sulfide respectively. The limitation of the phenol biodegradation flow by phenol inhibition seemed to be related to the more important sensitivity of phenol-degrading bacteria. The up-flow anaerobic sludge bed reactor operating in a non-phenol-dependent inhibition condition did not present any sensitivity to sulfide concentrations below 9.6 mmol dm,3. At this residual concentration, the pH and bisulfide ions' concentration might be responsible for the general collapsing of the reactor activity. Copyright © 2004 Society of Chemical Industry [source] Simultaneous organic carbon and nitrogen removal in an SBR controlled at low dissolved oxygen concentrationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2001Peng Dangcong Abstract Simultaneous organic carbon and nitrogen removal was studied in a sequencing batch reactor (SBR) fed with synthetic municipal wastewater and controlled at a low dissolved oxygen (DO) level (0.8,mg,dm,3). Experimental results over a long time (120 days) showed that the reactor achieved high treatment capacities (organic and nitrogen loading rates reached as high as 2.4,kg COD m,3 d,1 and 0.24,kg NH3 -N m3 d,1) and efficiencies (COD, NH3 -N and total nitrogen removal efficiencies were 95%, 99% and 75%). No filamentous bacteria were found in the sludge even though the reactor had been seeded with filamentous bulking sludge. Instead, granular sludge, which possessed high activity and good settleability, was formed. Furthermore, the sludge production rate under low DO was less than that under high DO. Significant benefits, such as low investment and less operating cost, will be obtained from the new process. © 2001 Society of Chemical Industry [source] Modeling and simulation of the formation and utilization of microbial products in aerobic granular sludgeAICHE JOURNAL, Issue 2 2010Bing-Jie Ni Abstract A mathematical model is established to simulate the formation of extracellular polymeric substances (EPS), soluble microbial products (SMP), and internal storage products (XSTO) in aerobic granular sludge. The sensitivity of these microbial products concentrations toward the key model parameters is analyzed. Independent experiments are conducted to find required parameter values and to test its predictive ability. The model is evaluated by using one-cycle operating experimental results of a lab-scale aerobic granule-based sequencing batch reactor (SBR) and batch experimental results. Results show that the model is able to describe the microbial product dynamics in aerobic granules and provide further insights into a granule-based SBR. The effect of the initial substrate and biomass concentrations on the formation of microbial products in aerobic granular sludge can therefore be analyzed by model simulation. A higher substrate concentration results in a greater concentration of EPS, SMP, and XSTO. An accumulation of biomass in the bioreactor leads to an increased production rate of EPS, SMP, and XSTO. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Cultivation of low-temperature (15°C), anaerobic, wastewater treatment granulesLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2009J. O'Reilly Abstract Aims:, Anaerobic sludge granules underpin high-rate waste-to-energy bioreactors. Granulation is a microbiological phenomenon involving the self-immobilization of several trophic groups. Low-temperature anaerobic digestion of wastes is of intense interest because of the economic advantages of unheated bioenergy production technologies. However, low-temperature granulation of anaerobic sludge has not yet been demonstrated. The aims of this study were to (i) investigate the feasibility of anaerobic sludge granulation in cold (15°C) bioreactors and (ii) observe the development of methanogenic activity and microbial community structure in developing cold granules. Methods and Results:, One mesophilic (R1; 37°C) and two low-temperature (R2 and R3, 15°C) laboratory-scale, expanded granular sludge bed bioreactors were seeded with crushed (diameter <0·4 mm) granules and were fed a glucose-based wastewater for 194 days. Bioreactor performance was assessed by chemical oxygen demand removal, biogas production, granule growth and temporal methanogenic activity. Granulation was observed in R2 and R3 (up to 33% of the sludge). Elevated hydrogenotrophic methanogenesis was observed in psychrophilically cultivated biomass, but acetoclastic methanogenic activity was also retained. Denaturing gradient gel electrophoresis of archaeal 16S rRNA gene fragments indicated that a distinct community was associated with developing and mature granules in the low-temperature (LT) bioreactors. Conclusions:, Granulation was observed at 15°C in anaerobic bioreactors and was associated with H2/CO2 -mediated methanogenesis and distinct community structure development. Significance and Impact of the Study:, Granulation underpins high-rate anaerobic waste treatment bioreactors. Most LT bioreactor trials have employed mesophilic seed sludge, and granulation <20°C was not previously documented. [source] Perturbation-independent community development in low-temperature anaerobic biological wastewater treatment bioreactorsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010Pádhraig Madden Abstract The reproducibility and stability of low- temperature anaerobic wastewater treatment systems undergoing transient perturbations was investigated. Three identical anaerobic expanded granular sludge bed-based bioreactors were used to degrade a volatile fatty acid and glucose-based wastewater under sub-ambient (15°C) conditions. The effect of a variety of environmental perturbations on bioreactor performance was assessed by chemical oxygen demand removal. Temporal microbial community development was monitored by denaturation gradient gel electrophoresis (DGGE) of 16S rRNA genes extracted from sludge granules. Methanogenic activity was monitored using specific methanogenic activity assays. Bioreactor performance and microbial population dynamics were each well replicated between both experimental bioreactors and the control bioreactor prior to, and after the implementation of most of the applied perturbations. Gene fingerprinting data indicated that Methanosaeta sp. were the persistent, keystone members of the archaeal community, and likely were pivotal for the physical stability and maintenance of the granular biofilms. Cluster analyses of DGGE data suggested that temporal shifts in microbial community structure were predominantly independent of the applied perturbations. Biotechnol. Bioeng. 2010;105: 79,87. © 2009 Wiley Periodicals, Inc. [source] Advanced monitoring of high-rate anaerobic reactors through quantitative image analysis of granular sludge and multivariate statistical analysisBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009J.C. Costa Abstract Four organic loading disturbances were performed in lab-scale EGSB reactors fed with ethanol. In load disturbance 1 (LD1) and 2 (LD2), the organic loading rate (OLR) was increased between 5 and 18.5 kg,COD,m,3,day,1, through the influent ethanol concentration increase, and the hydraulic retention time decrease from 7.8 to 2.5 h, respectively. Load disturbances 3 (LD3) and 4 (LD4) were applied by increasing the OLR to 50 kg,COD,m,3,day,1 during 3 days and 16 days, respectively. The granular sludge morphology was quantified by image analysis and was related to the reactor performance, including effluent volatile suspended solids, indicator of washout events. In general, it was observed the selective washout of filamentous forms associated to granules erosion/fragmentation and to a decrease in the specific acetoclastic activity. These phenomena induced the transitory deterioration of reactor performance in LD2, LD3, and LD4, but not in LD1. Extending the exposure time in LD4 promoted acetogenesis inhibition after 144 h. The application of Principal Components Analysis determined a latent variable that encompasses a weighted sum of performance, physiological and morphological information. This new variable was highly sensitive to reactor efficiency deterioration, enclosing variations between 27% and 268% in the first hours of disturbances. The high loadings raised by image analysis parameters, especially filaments length per aggregates area (LfA), revealed that morphological changes of granular sludge, should be considered to monitor and control load disturbances in high rate anaerobic (granular) sludge bed digesters. Biotechnol. Bioeng. 2009;102: 445,456. © 2008 Wiley Periodicals, Inc. [source] Hydrogenogenic CO Conversion in a Moderately Thermophilic (55 °C) Sulfate-Fed Gas Lift Reactor: Competition for CO-Derived H2BIOTECHNOLOGY PROGRESS, Issue 5 2006Jan Sipma Thermophilic (55 °C) sulfate reduction in a gas lift reactor fed with CO gas as the sole electron donor was investigated. The reactor was inoculated with mesophilic granular sludge with a high activity of CO conversion to hydrogen and carbon dioxide at 55 °C. Strong competition for H2 was observed between methanogens and sulfate reducers, while the homoacetogens present consumed only small amounts of H2. The methanogens appeared to be more sensitive to pH and temperature shocks imposed to the reactor, but could not be completely eliminated. The fast growth rates of the methanogens (generation time of 4.5 h) enabled them to recover fast from shocks, and they rapidly consumed more than 90% of the CO-derived H2. Nevertheless, steep increases in sulfide production in periods with low methane production suggests that once methanogenesis is eliminated, sulfate reduction with CO-rich gas as electron donor has great potential for thermophilic biodesulfurization. [source] Thermophilic (55,65 °C) and Extreme Thermophilic (70,80 °C) Sulfate Reduction in Methanol and Formate-Fed UASB ReactorsBIOTECHNOLOGY PROGRESS, Issue 5 2004Marcus V. G. Vallero The feasibility of thermophilic (55,65 °C) and extreme thermophilic (70,80 °C) sulfate-reducing processes was investigated in three lab-scale upflow anaerobic sludge bed (UASB) reactors fed with either methanol or formate as the sole substrates and inoculated with mesophilic granular sludge previously not exposed to high temperatures. Full methanol and formate degradation at temperatures up to, respectively, 70 and 75 °C, were achieved when operating UASB reactors fed with sulfate rich (COD/SO42 - = 0.5) synthetic wastewater. Methane-producing archaea (MPA) outcompeted sulfate-reducing bacteria (SRB) in the formate-fed UASB reactor at all temperatures tested (65,75 °C). In contrast, SRB outcompeted MPA in methanol-fed UASB reactors at temperatures equal to or exceeding 65 °C, whereas strong competition between SRB and MPA was observed in these reactors at 55 °C. A short-term (5 days) temperature increase from 55 to 65 °C was an effective strategy to suppress methanogenesis in methanol-fed sulfidogenic UASB reactors operated at 55 °C. Methanol was found to be a suitable electron donor for sulfate-reducing processes at a maximal temperature of 70 °C, with sulfide as the sole mineralization product of methanol degradation at that temperature. [source] Anaerobic digestion of Aegean olive mill effluents with and without pretreatmentJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2010Gülseren Pekin Abstract BACKGROUND: Olive oil production is an important economical activity in the Aegean region of Turkey. However, the effluents of the olive oil producing mills with their high organic loads and toxic compounds are causing serious environmental problems. The anaerobic biological treatment of olive mill wastewater (OMWW) using the treatment plants of the regional industries could be a method of choice and within the scope of this study floccular and granular sludges were investigated in batch mode for their success in the treatment of OMWW while producing biogas. The major limitation of this treatment is the inhibition of methanogenic bacteria by the phenolic compounds in OMWW. Thus an integrated solution was suggested in which a pre-treatment step (dephenolization) was also introduced before biological step. RESULTS: The effluents of 27 olive mills out of 47 were found to have total phenolics (TP) less than 3 g L,1 and could be treated anaerobically after simple dilution. The biogas production for the untreated OMWW was higher for floccular sludge than for the granular sludge (68.5 mL and 45.7 mL respectively). Combined pre-treatment experiments, first coagulation with polyaluminum chloride, followed by flocculation with cationic polyelectrolyte and finally Fenton's oxidation, could remove 80% of TP and 95% of the total suspended solids. CONCLUSION: OMWW having TP values less than 3 g L,1 can be treated anaerobically using floccular sludge after simple dilution and biogas can be produced. For OMWW samples having higher TP values pre-treatment is necessary and the pre-treatment given in this study may be used effectively. Copyright © 2010 Society of Chemical Industry [source] | |||||||||||||||||||||||||